The present invention relates to an apparatus and method for manufacturing a three-dimensional object. According to the apparatus and methods of the present invention, continuously variable diameter or controllable planar jets are used to form three-dimensional objects in an environment-controlled processing chamber. The apparatus and methods of the present invention are useful in the fields rapid prototyping and materials processing.
Manufacturing processes utilizing deposition techniques have been developed for rapid and flexible prototyping of three-dimensional parts and tooling. For example. U.S. Pat. Nos. 5,301,863, 5,301,415, 5,207,371 and 5,286,573 to Prinz et al. disclose conventional systems and methods for manufacturing three-dimensional objects by forming incremental buildup of layers on a work surface. In preferred embodiments of these inventions, thermal spray or weld deposition techniques are used to deposit object and support layers on a work surface.
Drop generators have also been developed and applied to the rapid prototyping of three-dimensional objects. See P. F. Jacobs, Rapid Prototyping and Manufacturing, ch. 16 (Society of Manufacturing Engineers, Dearborn, Mich. 1992). In a conventional drop generator of this type, molten metal is ejected as a uniform laminar liquid jet from a circular injector, or nozzle, located at the bottom of a heated reservoir. The uniform laminar liquid jet is broken into a series of uniform drops of desired size by selecting an injector diameter and varying the frequency of external oscillation near the injector or nozzle orifice. The uniform drops are then deposited in layers on a substrate surface where they solidify to form the desired three-dimensional metal product.
With this technique, the resulting metal products can be designed to have fine, equiaxed micro-structures without manufacturing defects such as porosity or alloy segregation. See C.-A. Chen, P. Acquaviva, J.-H. Chun and T. Ando, "Effects of Droplet Thermal Stale on Deposit Microstructure in Spray Forming", Scrilpta Materiala, vol. 34, pp. 689-696 (1996); J.-H. Chun and T. Ando, "Thermal Modeling of Deposit Solidification in Uniform Droplet Spray Forming," Proceedings of the 1996 NSF Design and Manufacturing Grantees Conference, pp. 353-354 (Society of Manufacturing Engineers 1996). This allows for a rapid one-time process for metal forming that does not require expensive and time-consuming post-processing of metal products.
However, despite these advantages, the manufacturing capabilities of conventional drop generators remain limited by the relatively small range of possible drop sizes. Greater variability in the drop size is desired to allow more efficient rapid prototyping by allowing the mass flux to be set according to the outline geometry and desired internal micro-structure of the product at a given point. Despite the variability of external oscillation, the possible range of drop sizes from a conventional drop generator is limited by the fixed injector diameter, which is typically less than one millimeter. Consequently, the liquid jet of a conventional drop generator remains laminar.
Therefore, a principle object of the present invention is to provide an apparatus and method for manufacturing a three-dimensional object utilizing a continuously variable diameter liquid jet to create variable drop sizes.
Another object of the present invention is to provide an apparatus and method for manufacturing a three-dimensional object utilizing a controllable laminar planar liquid jet to form a liquid sheet and create arrays of uniform molten metal drops.
A further object of the present invention is to provide an apparatus and method for manufacturing a three-dimensional object utilizing a piezoelectric oscillator and piezoelectric transducer circuit for creating continuously variable diameter and controllable planar jets.
Yet another object of the present invention is to provide an apparatus and method for manufacturing a three-dimensional object utilizing a position controllable platform.
Further objects, features and advantages of the invention will become apparent from the following detailed description taken in conjunction with the accompanying figures showing illustrative embodiments of the invention.